This is one of four independent but identical applications for a multi- center treatment study of panic disorder (PD) comprising the first study designed to assess the relative efficacy of a pharmacologic treatment, a cognitive behavioral panic control treatment and their combination for patients with PD. The study is designed as a 12 week acute treatment trial, followed by 6 months of maintenance treatment and 6 months of follow-up. PD is a prevalent chronic and debilitating disorder. Although some studies are available documenting the efficacy of both pharmacological and behavioral treatments for patients with agoraphobia, behavioral treatments for agoraphobia are very different from the newly developed cognitive behavioral treatments for PD. Preliminary studies suggest that these treatments may be quite effective. Surprisingly, few studies exist evaluating pharmacological treatments for PD without agoraphobia. Yet, a variety of evidence suggests that drugs are effective for panic attacks. It is also possible that the combination of psychological and pharmacological treatment will provide the optimal approach for many patients or that relapse rates after treatment discontinuation will differ. Central to this proposal is the collaboration of four research sites (SUNY Albany, Cornell, Hillside/ Columbia and Yale) representing both psychological and pharmacological orientations. The sites will enroll a total of 600 patients over 4 years. Patients will be randomly assigned to one of five treatment cells: imipramine (IMI) with medical management, pill placebo (PLA) with medical management, Panic Control Treatment (PCT) or a combination of PCT with either IMI or PLA. In addition to establishing relative efficacy, this design will allow us to establish guidelines for treatment of PD at site switch somewhat different orientations, identify comparative mechanisms of action of psycho- and pharmacotherapy, and introduce innovative methods to integrate medication and psychosocial treatment modalities for PD patients. An additional goal will be to examine the implication of prior psychoactive substance abuse for treatment outcome as well as the utilization of substances as coping mechanisms for anxiety and panic.